I have a complete article on this topic on www.teachingenglishgames.com/dirindex.htm
I also have a free mini-series that you can sign up for including games and activities, a free illustrated story called Hetty and the Lion, tips for storytelling and ideas for after telling the story.
Receive the free games and illustrated story for 3 to 5 year old children here: www.teachingenglishgames.com/3-5.htm
This is a great mini-series full of ideas and it serves as a free sample to my ebook dedicated to teaching children aged 3 to 5 English through games and stories.
I'll add a few comments to those already made:
Use real objects where possible and pictures where this is not feasible.
Use plenty of music and songs.
Use dance and movement.
Use stories as children love them and you will have a captive audience. Children absorb language subconsciously through songs and stories.
Vary the pace with movement and quiet sitting games to control the overall atmosphere.
Vary the activities and change games every five minutes or so.
Avoid spending too much time on colouring and elaborate arts and crafts if you only have a short session with the children - there are more effective ways to spend the time when it comes to language learning, although of course those activities are enriching in other ways but the children will most likely be doing them anyway outside of your language class.
There is much more on my articles page as mentioned above, and there are many ideas in the free mini-series.
I hope you enjoy it!
Shelley Ann Vernon www.teachingenglishgames.com/3-5.htm